docs: def _V_solver_error(self, Vtarget, D, L, horizontal, sideA, sideB, sideA_a,
                         sideB_a, sideA_f, sideA_k, sideB_f, sideB_k,
                         sideA_a_ratio, sideB_a_ratio):
          '''Function which uses only the variables given, and the TANK
          class itself, to determine how far from the desired volume, Vtarget,
          the volume produced by the specified parameters in a new TANK instance
          is. Should only be used by solve_tank_for_V method.
          '''
          a = TANK(D=float(D), L=float(L), horizontal=horizontal, sideA=sideA, sideB=sideB,
                   sideA_a=sideA_a, sideB_a=sideB_a, sideA_f=sideA_f,
                   sideA_k=sideA_k, sideB_f=sideB_f, sideB_k=sideB_k,
                   sideA_a_ratio=sideA_a_ratio, sideB_a_ratio=sideB_a_ratio)
          error = abs(Vtarget - a.V_total)
          return error